Process of rendering paper moisture, grease and acid proof and solution therefor



Patented Aug. 16, 1932 UNITED STATES PATENT! OFFICE LOG-AN A. DILS, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG-DILS, INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE PROCESS OF RENDERING PAPER MOISTURE, GREASE AND ACID PROOF AND SOLUTION THEREFOR 1T0 Drawing.

This invention relates to a process of treating paper to render the same moisture, grease and acid proof and to solutions employed for that purpose, and has for one of its objects 5 to produce a wrapping paper which shall be highly transparent and of great strength, while at the same time it is proof against the action of the acids, alkalis, solvents, and moisture, and which shall not be affected by m alcohols, ethers. or esters. Such wrapping paper is of great value in putting up many commercial articles in prepared packages.

B reason of its transparency, the purchaser I of said articles can readily inspect the same in the package; the contents of the package will remain absolutely uncontaminated from any contact with the paper; grease or other constituents of the articles wrapped will not in any way affect its strength or transparen- Qu cy, and the contents of the package are adequately protected against moisture in the atmosphere.

Many efforts have heretofore been made to produce a wrapper for packages of this char- .m acter. The well known cellophane is an example of such wrapper, and papers in imitation of cellophane have also been produced, but whether by reason of the expense of manufacture or other inherent defects, they 3 have not, so far as I am informed, been eminently satisfactory. Furthermore, it is desirable in certain classes of packages to provide heavy papers which are not transparent, such as light cardboard for making cartons and the like, with an acid, moisture and grease resisting coat.

In practicing the present invention, a gelatinous mass isdissolved in hot water preferably at a temperature ranging from 140 to 150 F. Preferably a little more than half of this gelatinous mass is pure gelatin, to

which is added Irish moss in the proportion of about one-half that of the gelatin employed, and hide glue in the proportion of about one-half of the Irish moss. The Irish Application filed December 2, 1930. Serial No. 499,609.

moss acts as a filler and imparts a high gloss to the finished product, while the hide glue not only acts as a filler but toughens the paper treated thereby and also imparts elasticity thereto. Pure gelatin is expensive While the Irish moss and hide glue are cheap products, but unlike gelatin, they contain impurities which if permitted to remain, would impair the clear transparency of the paper treated thereby, imparting an undesirable, cloudy, and more or less speckled efi'ect thereto. By the present invention however, these impurities are removed from the solution before it is applied to the paper, with the result that the paper is rendered more elastic and tougher than would be the case if pure gelatin were used, and this at a reduced expense, while at the same time producing a paper as clearly transparent as would be the case if the higher priced gelatin alone were employed.

After the gelatin, Irish moss and hide glue are thoroughly dissolved in the water, there is added to the solution about one-third as much glycerin (by weight) as that of the total gelatinous mass (gelatin, Irish moss and hide glue) employed, and the temperature of the mlxture is brought to approximately 150 F. The glycerin acts as a plastic agent and tends to make the paper treated thereby tough, flexible, transparent and glossy. There is also added to the solution, preferably simultaneously with the glycerin, a suitable purifying agent to dissolve the impurities in the Irish moss and hide glue. For this purpose, there is preferably employed a very small amount of dimethylketone or dioxan or other suitable ketone. It is obvious that if purified Irish moss and hide glue are used, the ketone or equivalent purifying agent may be omitted. In order to pre- .vent decomposition, there is also added to the solution a small quantity of a suitable preservative agent, such as sodium benzoate.

The gelatins (Irish moss, gelatin, hide glue) and glycerin in and of themselves would form a tacky coating too soft for practical use, and there is therefore added a hardening ingredient which in the present instant consists of sodium aluminum sulphate and potassium aluminum sulphate, the amount of these two sulphates-employed being about one-eighth of the total amount of Irish moss, gelatin and hide glue (by weight) and the sodium aluminum sulphate being in the proportion of about one-half of the potassium aluminum sulphate. The sodium aluminum sulphate not only acts as a hardening agent but tends to make the coating brittle. The potassium aluminum sulphate on the other hand not only acts as a hardening agent but tends to make the coating elastic, and by using the two sulphates as hardening agents, the desired hardening effect is secured without destroying the desired elastic properties of the coating.

After the ingredients are thoroughly incorporated in the solution at a temperature of approximately 150 F. as indicated above, it will be found that the impurities in the gels are either precipitated to the bottom of the container or float as a foamy mass on the top of the solution. This foamy mass is carefully skimmed off and the solution then decanted, leaving the precipitated impurities in the bottom of the container. While the sodium benzoate may be incorporated at the same time as the dimethylketone (or other ketone) it is preferably added after the impurities are removed from the solution.

The solution thus constituted may be applied to the paper by dipping, brushing or otherwise. When thin paper is to be treated so as to render the same transparent as Well as possessing the other desirable characteristics indicated above, it is preferably dipped in the solution, but when heavier paper or cardboard is treated, and particularly when it is desired to treat but one side thereof, the solution is applied thereto by brushing or otherwise. In actual commercial operations, however, continuous Webs, either of the thin paper or of the cardboard or heavier paper to be treated, are advanced by suitable rolls by means of which, in the case of the thin paper, the web of paper is dipped into the solution contained in asuitable tank where it is maintained at a temperature of approximately 150 F. and as the web of paper passes from the tank, it is fed to squeeze rolls which operate to remove surplus material therefrom and to uniformly impregnate the paper with the coating filler. For the continuous application of the coating filler to heavier v paper or cardboard, the same is preferably passed continuously into contact with a roll which dips down into the coating solution and applies it to the web of paper as the same passes over the roll. If it were attempted to apply the solution as above described to the papers by means of such rolls as indicated above, the solution would soon, by reason of its tackiness, adhere to the rolls to such an extent as to render the operation of the machinery impossible, and there is therefore added to the solution before the same is applied to the papers, a suitable hardening or congealing agent, preferably in the form of 37% formaldehyde in the proportion of about one-fiftieth of the amount of the gels (Irish moss, gelatin and hide glue) employed. Care must be taken to add only a sufiicient amount of this hardening or congealing agent to relieve the solution of its tacky character, since the presence of any over-amount of such agent will tend to solidify the solution.

After the solution has been applied to the paper web, the same is dried, preferably by passing the same through a vertical drier equipped with hot air blasts supplied from a steam coil or other source.

After the paper with the solution applied thereto is thoroughly dried, the same is then treated, according to the present invention, in a suitable fixing bath to set and thoroughly harden the coating filler but without destroying its elastic properties. This fixing bath is preferably composed of 99% methyl spirits to which is added one pound avoirdupois, 37% formaldehyde and one ounce, avoirdupois. C. P. glycerin for each gallon of methyl spirits. The formaldehyde is a fixing or hardening agent and the glycerin acts to temper its hardening action while the methyl spirits serves as a carrying agent which quickly evaporates and thus facilitates the continuous practice of the invention with machinery.

The paper treated with the solution first described after being thoroughly dried is treated with this fixing solution gat a proximately room temperature, say 0 by dipping the same in the fixing solution-or otherwise applying the same. In the continuous process of treating webs of paper, the web is by preference passed under a submerged roll at the bottom of the container for the fixing bath, then upward through the fixing solution to glass scrapers which remove surplus liquid, from whence the web is passed through a vertical drying shaft supplied with heat, as by steam coils, from whence it is passed by means of suitable guiding rolls onto a winding roll as a finished product.

When but one side of a sheet or Web of paper is to be treated, it will of course be understood that the paper or web is not submerged in the fixing bath but is passed through suitable mechanism for applying the fixing solution to that surface and that surface only to which the coating or filling solution has been first applied.

While the proportions of the ingredients above mentioned may be varied within limits, experience has taught that solutions prepared in accordance with the following formulas give superior results, to wit:

Water pounds Irish moss 6 pounds Pure gelatin 13 pounds lIide glu 3 pounds Glycerin 8 4 pounds Dimethylketone pound Sodium benzoatc 4, pound Potassium aluminum sulphate 2 pounds Sodium aluminum sulphate 1 pound Formaldehyde, 37% pound and for the fixing bath Methyl spirits. 99% 10 gallons (1280 fluid ounces) Formaldehyde, 37% l0 pounds, avoirdupois, t. P. glycerin 10 ounces, avoirdupois.

lVhen the above formula is employed in treating light papers such as sulphlte papers,

it will be found that the paper is rendered remarkably transparent and very tough. Moreover, the coating whether app-lied to thin papers or to cardboard or other heavy paper, will be found to be moisture proof, grease proof, acid proof (lactic acid excepted), alkali proof and solvent proof. It will not be affected by alcohols, ethers or esters.

What is claimed is:

1. The solution for treating paper which comprises the following ingredients in approximately the following proportions, to wit: pure gelatin 13 pounds, Irish moss 6 pounds, hide glue 3 pounds, glycerin 8 A pounds, dimethylketone' pounds, sodium benzoate A; pound, potassium aluminum sulphate 2 pounds, sodium aluminum sulphate 1 pound, and formaldehyde pound, dissolved in 65 pounds of water.

2. The process of treating paper which consists in applying thereto the solution defined in claim 1, drying the same, and then subjecting the same to the action of a fixing bath comprised of 99% methyl spirits, 37% formaldehyde and glycerin in the proportions of methyl spirits 10 gallons (1280 fluid ounces) formaldehyde 10 pounds, avoirdupois, and glycerin 10 ounces, avoirdupois.

3. The process of treating paper which con sists in dissolving in water approximately 23 pounds of gelatinous substances, a purifying agent for the said gelatinous substances, 8'

pounds of glycerin, 1 pound sodium aluminum sulphate, 2 pounds of potassium aluminum sulphate and a small quantity of formaldehyde, heating the solution, applying the solution to the paper, then drying the paper and applying a fixing bath thereto.

4. The process of treating paper which consists in dissolving in water approximately 23 pounds of gelatinous substances, a purifying agent for the said gelatinous substances, 8 pounds of glycerin, 1 pound sodium aluminum sulphate, 2 pounds of potassium aluminum sulphate and a small quantity of formaldehyde,-heating the solution, applying the solution to the paper, then drying the paper and applylng thereto a fixing bath composed of 99% methyl spirits, 37% formaldehyde and C. P. glycerin in the proportions of 10 gallons (1280 fluid ounces) methyl spirits, 10 pounds (avoirdupois) formaldehyde, and 10 ounces (avoirdupois) glycerin.

5. A solution for treating paper, made by dissolving in water the following substances in approximately the following proportions, to wit: 24 pounds of gelatinous substances, and a purifying agent for said substances, then adding approximately one third as much pure glycerin as gelatinous substances, one quarter as much potassium alummum sulphate as glycerin, one half as much sodium aluminum sulphate as potassium aluminum sulphate, and one half as much 37% formaldehyde as sodium aluminum sulphate, heating the solution to approximately 150 F., skimming oil the impurities that rise to the surface and then decanting the solution.

In testimony whereof I have signed this specification.

LOGAN A. DILS. 

